The present invention relates generally to the field of safety barriers and more particularly to a system for maintaining tension in safety wires.
It is common practice in the construction industry to build a temporary or movable platform for a construction worker to stand on, and for supporting tools and materials. The platform may be supported by the ground, or may be suspended from above, or may be attached to a nearby large object such as the side of a ship. The platform may also be known as scaffolding, or staging. The platform may be used for constructing ships or constructing buildings.
It is common practice to place a safety barrier along the outside of the platform, in order to prevent the construction worker from falling from the platform. Falling from the platform may severely injure or kill the construction worker. Similarly, safety barriers may be placed around the perimeter of a dangerous hole or dangerous machinery. The term platform is defined broadly, and includes any approximately horizontal working surface from which a worker may fall. For example, the deck of a ship may be a platform.
Specifically, one common practice in the industry is to rig a safety strand through posts spaced at regular intervals along one or more edges of the platform. These posts may also be known as safety uprights, poles, or stanchions. The posts may be formed from any rigid member such as steel or iron channel stock having a hollow rectangular cross section, angle iron stock with an “L” shaped cross section, or pipe. The posts may be integrated into a support bracket for the platform, and the support bracket may be bolted or welded to the side of a ship or other structure. Horizontal wood or aluminum decking may link the support brackets to create a horizontal working platform.
The posts are typically linked with a safety strand in the form of a steel cable, or other line to prevent the construction worker from accidentally falling from the exterior edges of the platform. The steel cable may be positioned at any height, but is typically positioned at about waist high (about four feet high) above the horizontal surface of the platform. Additional cables may be positioned at other heights for additional safety. For example a second cable may be positioned horizontally at about two feet high. At the end of the platform, the cables may be attached directly to the structure.
The safety strand is attached to the vertical posts by various fastening techniques. One conventional fastening technique involves threading the cable through a hole in the post, looping the cable around the post and then proceeding to the next post. This technique, which may be referred to as “round turn” technique may also include forming a simple overhand knot to secure the strand to the post.
One problem with the round turn technique is that it requires the strand to be relatively flexible. This may place limitations on the material or diameter of the strand. In some cases, the strand may be sufficiently flexible to form a knot, but the resulting attachment may be relatively loose. This, in turn, may limit the ability to maintain sufficient tension in the strand.
Another problem with the round turn approach is that, even if a high degree of tension can be established initially, it may be difficult to maintain this tension. Workers have a tendency to lean on safety strands or place materials against them, which places the strand under additional tension. Application and removal of such additional loads can cause the strands to slacken over time.
The present invention eliminates the “round turn” technique, and creates a stable and secure attachment of the cable to the post. This stable and secure attachment creates and maintains a tight cable with relatively high tension.